1 files changed, 60 insertions, 20 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b0c338ecc318..f40d850ebabc 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2002,7 +2002,6 @@ static void tracing_reset_cpu(struct array_buffer *buf, int cpu)
 void tracing_reset_online_cpus(struct array_buffer *buf)
 {
 	struct trace_buffer *buffer = buf->buffer;
-	int cpu;
 
 	if (!buffer)
 		return;
@@ -2014,8 +2013,7 @@ void tracing_reset_online_cpus(struct array_buffer *buf)
 
 	buf->time_start = buffer_ftrace_now(buf, buf->cpu);
 
-	for_each_online_cpu(cpu)
-		ring_buffer_reset_cpu(buffer, cpu);
+	ring_buffer_reset_online_cpus(buffer);
 
 	ring_buffer_record_enable(buffer);
 }
@@ -2931,12 +2929,6 @@ static void __ftrace_trace_stack(struct trace_buffer *buffer,
 		skip++;
 #endif
 
-	/*
-	 * Since events can happen in NMIs there's no safe way to
-	 * use the per cpu ftrace_stacks. We reserve it and if an interrupt
-	 * or NMI comes in, it will just have to use the default
-	 * FTRACE_STACK_SIZE.
-	 */
 	preempt_disable_notrace();
 
 	stackidx = __this_cpu_inc_return(ftrace_stack_reserve) - 1;
@@ -3136,6 +3128,9 @@ static int alloc_percpu_trace_buffer(void)
 {
 	struct trace_buffer_struct *buffers;
 
+	if (trace_percpu_buffer)
+		return 0;
+
 	buffers = alloc_percpu(struct trace_buffer_struct);
 	if (MEM_FAIL(!buffers, "Could not allocate percpu trace_printk buffer"))
 		return -ENOMEM;
@@ -3338,6 +3333,26 @@ int trace_array_vprintk(struct trace_array *tr,
 	return __trace_array_vprintk(tr->array_buffer.buffer, ip, fmt, args);
 }
 
+/**
+ * trace_array_printk - Print a message to a specific instance
+ * @tr: The instance trace_array descriptor
+ * @ip: The instruction pointer that this is called from.
+ * @fmt: The format to print (printf format)
+ *
+ * If a subsystem sets up its own instance, they have the right to
+ * printk strings into their tracing instance buffer using this
+ * function. Note, this function will not write into the top level
+ * buffer (use trace_printk() for that), as writing into the top level
+ * buffer should only have events that can be individually disabled.
+ * trace_printk() is only used for debugging a kernel, and should not
+ * be ever encorporated in normal use.
+ *
+ * trace_array_printk() can be used, as it will not add noise to the
+ * top level tracing buffer.
+ *
+ * Note, trace_array_init_printk() must be called on @tr before this
+ * can be used.
+ */
 __printf(3, 0)
 int trace_array_printk(struct trace_array *tr,
 		       unsigned long ip, const char *fmt, ...)
@@ -3345,12 +3360,16 @@ int trace_array_printk(struct trace_array *tr,
 	int ret;
 	va_list ap;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
-		return 0;
-
 	if (!tr)
 		return -ENOENT;
 
+	/* This is only allowed for created instances */
+	if (tr == &global_trace)
+		return 0;
+
+	if (!(tr->trace_flags & TRACE_ITER_PRINTK))
+		return 0;
+
 	va_start(ap, fmt);
 	ret = trace_array_vprintk(tr, ip, fmt, ap);
 	va_end(ap);
@@ -3358,6 +3377,27 @@ int trace_array_printk(struct trace_array *tr,
 }
 EXPORT_SYMBOL_GPL(trace_array_printk);
 
+/**
+ * trace_array_init_printk - Initialize buffers for trace_array_printk()
+ * @tr: The trace array to initialize the buffers for
+ *
+ * As trace_array_printk() only writes into instances, they are OK to
+ * have in the kernel (unlike trace_printk()). This needs to be called
+ * before trace_array_printk() can be used on a trace_array.
+ */
+int trace_array_init_printk(struct trace_array *tr)
+{
+	if (!tr)
+		return -ENOENT;
+
+	/* This is only allowed for created instances */
+	if (tr == &global_trace)
+		return -EINVAL;
+
+	return alloc_percpu_trace_buffer();
+}
+EXPORT_SYMBOL_GPL(trace_array_init_printk);
+
 __printf(3, 4)
 int trace_array_printk_buf(struct trace_buffer *buffer,
 			   unsigned long ip, const char *fmt, ...)
@@ -5886,7 +5926,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
 	}
 
 	/* If trace pipe files are being read, we can't change the tracer */
-	if (tr->current_trace->ref) {
+	if (tr->trace_ref) {
 		ret = -EBUSY;
 		goto out;
 	}
@@ -6102,7 +6142,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 
 	nonseekable_open(inode, filp);
 
-	tr->current_trace->ref++;
+	tr->trace_ref++;
 out:
 	mutex_unlock(&trace_types_lock);
 	return ret;
@@ -6121,7 +6161,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
 
 	mutex_lock(&trace_types_lock);
 
-	tr->current_trace->ref--;
+	tr->trace_ref--;
 
 	if (iter->trace->pipe_close)
 		iter->trace->pipe_close(iter);
@@ -7405,7 +7445,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 	if (ret)
 		return ret;
 
-	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	info = kvzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info) {
 		trace_array_put(tr);
 		return -ENOMEM;
@@ -7423,7 +7463,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 
 	filp->private_data = info;
 
-	tr->current_trace->ref++;
+	tr->trace_ref++;
 
 	mutex_unlock(&trace_types_lock);
 
@@ -7524,14 +7564,14 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
 
 	mutex_lock(&trace_types_lock);
 
-	iter->tr->current_trace->ref--;
+	iter->tr->trace_ref--;
 
 	__trace_array_put(iter->tr);
 
 	if (info->spare)
 		ring_buffer_free_read_page(iter->array_buffer->buffer,
 					   info->spare_cpu, info->spare);
-	kfree(info);
+	kvfree(info);
 
 	mutex_unlock(&trace_types_lock);
 
@@ -8732,7 +8772,7 @@ static int __remove_instance(struct trace_array *tr)
 	int i;
 
 	/* Reference counter for a newly created trace array = 1. */
-	if (tr->ref > 1 || (tr->current_trace && tr->current_trace->ref))
+	if (tr->ref > 1 || (tr->current_trace && tr->trace_ref))
 		return -EBUSY;
 
 	list_del(&tr->list);